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JplDE421 Class

Represents JPL DE421 ephemeris data.
Inheritance Hierarchy

Namespace:  AGI.Foundation.Celestial
Assembly:  AGI.Foundation.Models (in AGI.Foundation.Models.dll) Version: 24.2.419.0 (24.2.419.0)
Syntax
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public class JplDE421 : JplDE, IJplDEWithMoonLibrationModel

The JplDE421 type exposes the following members.

Constructors
  NameDescription
Public methodJplDE421(JplDEFile)
Initializes an instance using the specified JplDEFile instance.
Public methodJplDE421(StreamFactory)
Initializes a new instance with the specified stream factory.
Public methodJplDE421(String)
Initializes an instance using the specified JPL DE filename.
Protected methodJplDE421(JplDE421, CopyContext)
Initializes a new instance as a copy of an existing instance.
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Properties
  NameDescription
Public propertyEarthMoonMassRatio
Gets the ratio of the mass of the earth to the mass of the moon.
(Inherited from JplDE.)
Public propertyEarthRadius
Gets the radius of Earth in kilometers.
Public propertyFile
Gets the raw JPL DE file represented by this instance.
(Inherited from JplDE.)
Public propertyFinalEpoch
Gets the last epoch for which ephemeris data is available.
(Inherited from JplDE.)
Public propertyInitialEpoch
Gets the first epoch for which ephemeris data is available.
(Inherited from JplDE.)
Public propertyIsFrozen
Gets a value indicating whether this object is frozen. A frozen object cannot be modified and an ObjectFrozenException will be thrown if an attempt is made to do so.
(Inherited from DefinitionalObject.)
Public propertyKilometersPerAstronomicalUnit
Gets the number of kilometers (km) in one astronomical unit (AU).
(Inherited from JplDE.)
Public propertyLunarEphemerisNumber
Gets the number indicating the source of the data. For example, '405' indicates the DE405 ephemerides.
(Inherited from JplDE.)
Public propertyMarsRadius
Gets the radius of Mars in kilometers.
Public propertyMercuryRadius
Gets the radius of Mercury in kilometers.
Public propertyPlanetaryEphemerisNumber
Gets the number indicating the source of the data. For example, '405' indicates the DE405 ephemerides.
(Inherited from JplDE.)
Public propertySource
Gets the string describing the source of the data.
Public propertySpeedOfLight
Gets the speed of light in km/s.
(Inherited from JplDE.)
Public propertyTitles
Gets the collection of titles.
(Inherited from JplDE.)
Public propertyVenusRadius
Gets the radius of Venus in kilometers.
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Methods
  NameDescription
Protected methodCheckForSameDefinition(DefinitionalObject)
Checks to determine if another instance has the same definition as this instance and returns if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IsSameDefinition(Object).
(Inherited from JplDE.)
Protected methodCheckForSameDefinition(JplDE)
Checks to determine if another instance has the same definition as this instance and returns if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IsSameDefinition(Object).
(Overrides JplDECheckForSameDefinition(JplDE).)
Protected methodCheckForSameDefinition(JplDE421)
Checks to determine if another instance has the same definition as this instance and returns if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IsSameDefinition(Object).
Public methodClone
Clones this object using the specified context.
(Overrides DefinitionalObjectClone(CopyContext).)
Protected methodComputeCurrentDefinitionHashCode
Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the CheckForSameDefinition(DefinitionalObject) method.
(Overrides JplDEComputeCurrentDefinitionHashCode.)
Public methodCreateEarthMoonBarycenterPoint
Creates a Point that represents the position of the Earth-Moon barycenter calculated from the data in this class.
(Inherited from JplDE.)
Public methodEnumerateDependencies
Enumerates the dependencies of this object by calling EnumerateT(T) for each object that this object directly depends upon. Derived classes which contain additional dependencies MUST override this method, call the base implementation, and enumerate dependencies introduced by the derived class.
(Inherited from JplDE.)
Public methodEquals
Determines whether the specified object is equal to the current object.
(Inherited from Object.)
Protected methodFinalize
Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.
(Inherited from Object.)
Public methodFreeze
Freezes this object. Further attempts to modify it will result in an ObjectFrozenException.
(Inherited from DefinitionalObject.)
Protected methodFreezeAggregatedObjects
Called by Freeze to also freeze any objects that are considered to be a part of this object. Derived classes which contain additional aggregated objects MUST override this method, call the base implementation, and freeze aggregated objects introduced by the derived class. The objects that need to be frozen in this method are frequently created in this object's constructor and are not settable via properties.
(Inherited from JplDE.)
Public methodGetCenterOfMassPoint
Gets a point which represents the center of mass of the given JplDECentralBody.
(Inherited from JplDE.)
Public methodGetDefinitionHashCode
Gets a hash code representing the definition of this object.
(Inherited from DefinitionalObject.)
Public methodGetEarthNutationModel
Creates a NutationModel which uses this JPL DE data for the nutation of the Earth.
(Inherited from JplDE.)
Public methodGetGravitationalParameter
Gets the gravitational parameter of a central body in SI units (m^3/s^2).
(Inherited from JplDE.)
Public methodGetGravitationalParameterNative
Gets the gravitational parameter of a central body in AU^3/day^2.
(Inherited from JplDE.)
Public methodGetHashCode
Serves as the default hash function.
(Inherited from Object.)
Public methodGetMoonFixedFrame
Uses the JplDE421 data to return the orientation and position of the Moon's principal axes of inertia to define a fixed frame. This is useful as a frame in which to describe the gravity of the Moon.
Public methodGetMoonLibrationModel
Gets a libration model for the Moon.
Public methodGetMoonTopographicFixedFrame
Uses the JplDE421 data to return the orientation and position of the Moon's "Mean Earth" axes which define a fixed frame with the z-axis pointing toward the mean axis of rotation, the x-axis pointing toward the mean direction to the Earth, and the y-axis orthogonal. This is useful for describing topographic features on the Moon.
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodIsSameDefinition
Determines if this object has the same definition as another object.
(Inherited from DefinitionalObject.)
Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Protected methodThrowIfFrozen
Throws ObjectFrozenException if this object IsFrozen. This method should be called from any method or property that modifies this object.
(Inherited from DefinitionalObject.)
Public methodToString
Returns a string that represents the current object.
(Inherited from Object.)
Public methodCode exampleUseForCentralBodyPositions

Uses this JPL DE data for the positions of the centers of mass of the central bodies in the specified CentralBodiesFacet instance. This also sets the positions of all the PlanetarySystemBarycenters.

In particular, the EarthMoonBarycenter is calculated using the EarthMoonMassRatio and the updated positions of EarthCentralBody and MoonCentralBody. The other planetary system barycenters are set to exactly the same positions as their respective planets because technically the JPL DE data provides the barycenter positions rather than the physical positions of those planets.

(Inherited from JplDE.)
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Fields
  NameDescription
Public fieldStatic memberEphemerisNumber
The PlanetaryEphemerisNumber represented by this class.
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Remarks
JPL Planetary Ephemeris files can be downloaded from https://ftp.agi.com/pub/STKData/Astro/PlanetEphem/lendian/.
Examples

The following example shows how to load a JPL DE file and use its data for the positions of the centers of mass of the central bodies in a CentralBodiesFacet:

C#
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// Load a JplDE file using a string that represents the JplDE file
JplDE421 jplde = new JplDE421(Path.Combine(dataPath, "plneph.421"));

// Use the JplDE data in a CentralBodiesFacet
CentralBodiesFacet centralBodies = CentralBodiesFacet.GetFromContext();
jplde.UseForCentralBodyPositions(centralBodies);

// Optional - use the JplDE data for the Lunar fixed frame
MoonCentralBody moon = centralBodies.Moon;
moon.FixedFrame = jplde.GetMoonFixedFrame();
See Also